A need exists for an efficient furnace system which may be used to melt scrap metal. The most commonly used furnace systems for melting scrap, particularly non-ferrous metal scrap, require preheating of the scrap at one location and then moving the preheated scrap into a furnace for melting. Heretofore, the relatively low cost of fuel for a furnace made it uneconomical to employ sophisticated devices or techniques in an effort to reduce operating costs. However, it is becoming necessary that a melting furnace, or the like, be operated more efficiently.
A conventional secondary aluminum melting plant operates generally according to the following process. The scrap is sorted and thermally purified and dried in processing equipment. The scrap is then dumped into the furnace where it is melted, but it is known that dumping cold metals into a furnace can cause the furnace temperature to be reduced to an extent which is detrimental to furnace efficiency. Furthermore, when cold metals are dumped into molten metal, there is a danger of explosion due to the moisture which may be present in such cold metals.
One method to operate a furnace in a more efficient manner is the utilization of some form of device to extract heat from the hot gases discharged from the furnace and using the extracted gases for one or more purposes in connection with the operation of the furnace. It has been proposed to heat and melt a charge of material in a melting chamber and convey the hot exhaust gases from the melting chamber to another chamber for the purpose of preheating another charge of material.
Accordingly, it is desirable to provide a continuous preheat charging system. The present invention is directed toward providing an improved scrap preheating apparatus.